{"discovery":{"who":"LINEAR","location":"Socorro","name":"Sheward","site":null,"discovery":"","date":"1999-Dec-06","citation":"Daniel Sheward (b. 1995) is a British planetary scientist whose work focuses on the detection of fresh impact craters on the Moon.  His use of the Moon as a natural space laboratory enables the linking of meteoroids to their resulting craters, advancing our understanding of impact-scaling laws and contributing to fundamental impact physics and space safety.","ref":"20010109/Numbers.arc","cref":"WGSBN Bull. 6, #11, 33"},"signature":{"version":"1.3","source":"NASA/JPL Small-Body Database (SBDB) API"},"object":{"orbit_id":"71","fullname":"20713 Sheward (1999 XA32)","orbit_class":{"code":"MBA","name":"Main-belt Asteroid"},"pha":false,"neo":false,"spkid":"20020713","kind":"an","des":"20713","prefix":null,"shortname":"20713 Sheward"},"phys_par":[{"notes":null,"name":"H","sigma":null,"units":null,"ref":"E2025-UR3","title":"absolute magnitude","desc":"absolute magnitude (magnitude at 1 au from Sun and observer)","value":"12.02"},{"units":"km","sigma":"0.251","notes":null,"name":"diameter","desc":"effective body diameter","value":"20.690","ref":"urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)","title":"diameter"},{"desc":"body rotation period (synodic)","value":"3.5","ref":"LCDB (Rev. 2023-October); Warner et al., 2009","title":"rotation period","units":"h","sigma":null,"notes":"[Result based on less than full coverage, so that the period may be wrong by 30 percent or so.]  REFERENCE LIST:[Waszczak, A.; Chang, C.-K.; Ofeck, E.O.; Laher, F.; et al. (2015) Astron. J. 150, A75.], [DeGraff, D.R. (2017) Minor Planet Bull. 44, 350-354.]","name":"rot_per"},{"ref":"urn:nasa:pds:neowise_diameters_albedos::2.0[mainbelt] (http://adsabs.harvard.edu/abs/2011ApJ...741...68M)","title":"geometric albedo","value":"0.086","desc":"geometric albedo","notes":null,"name":"albedo","units":null,"sigma":"0.016"}],"orbit":{"condition_code":"0","model_pars":[],"producer":"Otto Matic","orbit_id":"71","first_obs":"1953-10-09","n_del_obs_used":null,"not_valid_before":null,"data_arc":"26416","source":"JPL","not_valid_after":null,"rms":"0.38","pe_used":"DE441","equinox":"J2000","moid_jup":"1.76","last_obs":"2026-02-04","sb_used":"SB441-N16","epoch":"2461200.5","cov_epoch":"2458820.5","t_jup":"3.164","elements":[{"name":"e","units":null,"sigma":"6.8e-10","label":"e","title":"eccentricity","value":"0.109"},{"value":"3.14","title":"semi-major axis","label":"a","units":"au","sigma":"1.3e-09","name":"a"},{"name":"q","units":"au","sigma":"1.3e-09","title":"perihelion distance","label":"q","value":"2.8"},{"label":"i","title":"inclination; angle with respect to x-y ecliptic plane","value":"12.7","name":"i","units":"deg","sigma":"3e-08"},{"title":"longitude of the ascending node","label":"node","value":"290","name":"om","sigma":"9.2e-08","units":"deg"},{"label":"peri","title":"argument of perihelion","value":"285","name":"w","sigma":"2.6e-07","units":"deg"},{"name":"ma","sigma":"3.8e-07","units":"deg","label":"M","title":"mean anomaly","value":"195"},{"value":"2462129.044","title":"time of perihelion passage","label":"tp","units":"TDB","sigma":"2.6e-06","name":"tp"},{"name":"per","units":"d","sigma":"1.3e-06","title":"sidereal orbital period","label":"period","value":"2030"},{"units":"deg/d","sigma":"1.1e-10","name":"n","value":"0.177","title":"mean motion","label":"n"},{"sigma":"1.5e-09","units":"au","name":"ad","value":"3.48","label":"Q","title":"aphelion distance"}],"moid":"1.82","comment":null,"soln_date":"2026-06-05 18:02:48","n_obs_used":5354,"two_body":null,"n_dop_obs_used":null}}